1. Field of the Invention
This invention relates to iron compounds for use in pharmaceutical compositions for the treatment of iron deficiency anaemia.
2. Discussion of the Background
An adequate supply of iron to the body is an essential requirement for tissue growth in both man and animals. Although there is normally an ample amount of iron in the diet, the level of absorption of iron from food is generally low so that the supply of iron to the body can easily become critical under a variety of conditions. Iron deficiency anaemia is commonly encountered in pregnancy and may also present a problem in the newly born, particularly in certain animal species such as the pig. Moreover, the certain pathological conditions there is a mal distribution of body iron leading to a state of chronic anaemia. This is seen in chronic diseases such as rheumatoid arthritis, certain haemolytic diseases and cancer.
Although a wide range of iron compounds is already marketed for the treatment of iron deficiency anaemia, the level of iron uptake by the body from these compounds is often quite low, necessitating the administration of relatively high dosage levels of the compound. The administration of high dose, poorly absorbed, iron complexes may cause siderosis of the gut wall and a variety of side effects such as nausea, vomiting, constipation and heavy malodorous stools.
In the UK patent applications of numbers (a) 8308053 (published as GB 2117766A), (b) 8327612 (published as GB 2128998A) and (c) 8407180 (published as GB 2136806A), and in corresponding applications filed the USA: (a) U.S. application Ser. No. 478,494 granted as U.S. Pat. No. 4,550,101 (b) U.S. applications Ser. Nos. 542,976 (granted as U.S. Pat. No. 4,575,502), 601,485 and 717,660, and (c) U.S. application Ser. No. 592,543); we describe iron complexes of various 3-hydroxpyrid-2-ones, 3-hydroxypyrid-4-ones and 3-hydroxy-4-pyrones which we have identified as being of particular value for use at relatively low dosage levels in the treatment of iron deficiency anaemia. It has now been found that certain advantages, as discussed hereinafter, accrue from the use of complexes not described in these earlier applications which contain one or more hydroxypyridone or hydroxypyrone ligands but in which the ligands present in the complex are not identical.